cbhacking writes "In June of 2012, Microsoft announced that they would be providing a system whereby "registered [Windows Phone] enthusiasts get early access to updates" without waiting for carrier approval and broad distribution. For more than a year, that has been an unfulfilled promise, and for many users, updates have been delayed or may even still be unavailable. Today, coinciding with the release of WP8 Update 3 (a.k.a. GDR3), Microsoft is allowing "developers" (anybody who has enabled app sideloading on their phone) to opt into a "Windows Phone Preview" program to allow updating immediately.
Like the update itself, this is likely a move in response to consumer demand and comparisons to iOS and Android, as there is little in the update which specifically interests developers. However, the program does warn that participation may invalidate your device's warranty; this may have been required by the carriers to relieve concerns of high support costs in the event of a botched update. While only the Microsoft portion of the updates (as opposed to driver firmware or OEM customizations) are available through this program, participating phones will also continue to receive public updates as they are rolled out."